Multiple audio outputs

Hi there.
is it possible to use a USB sound card as a secondary output in CrossDJ on OS X Yosemite, so that i can use it to preview tracks on my headphones?
If yes... how is it done, and where would i find some instructions?
I have searched on line, but can't quite seem to get it working.
is it possible to use a USB sound card as a secondary output in CrossDJ on OS X Yosemite, so that i can use it to preview tracks on my headphones?
If yes... how is it done, and where would i find some instructions?
I have searched on line, but can't quite seem to get it working.